The present invention relates to a bracket for orthodontic appliances.
It is known that orthodontic appliances utilized for correcting the position and/or orientation of the teeth in a patient generally consist of an archwire made of a metal material and a plurality of brackets. Each bracket has a suitable housing seat on one side for engagement of the archwire, while on the opposite side said bracket is secured to a tooth; in this way, by arranging the archwire following predetermined conformations, a corrective action can be exerted on one or more teeth so as to improve position and inclination of same.
The presently-used brackets comprise a substantially rectangular base on a face of which a pair of hooks is welded; the hooks engage the archwire of circular section, whereas the opposite base face is fastened to the tooth generally through suitable composite materials.
By means of brackets as briefly described above, a rotation around the vertical axis of the tooth can be applied to the tooth itself and/or also a rotation around a horizontal axis oriented transversely of the tooth from the inside to the outside of the oral cavity (in the vestibulum-lingualis direction).
Rotations around the meso-distal axis of the tooth can be also applied, i.e. rotations around a horizontal axis substantially orthogonal to the vestibulum-lingualis axis; these rotations (also referred to as “torque”) are carried out through use of an archwire or sectionals of rectangular section.
The brackets used in this case are provided with a groove having a shape suitably conforming to that of the archwire which is inserted thereinto on accomplishment of the orthodontic appliance.
However, through a single archwire of rectangular section only forces of limited intensity can be applied to the tooth; in particular the imposed torque for a rotation around the meso-distal axis (i.e. for a rotation in the vestibulum-lingualis direction) is limited by the sizes of the transverse section of the archwire itself. Therefore, for increasing the intensity of this torque (for teeth requiring important torque corrections, for example), the sizes of the archwire section should be correspondingly increased, which will make said archwire practically unusable.